PHP取出素数并且求和

//PHP取出素数并且求和
 1 function primes($n,$s = false) {
 2     $primes = array_fill(2,$n - 1,'prime');
 3     for ($i = 2,$range = intval(sqrt($n)); $i < $range ;$i++) {
 4         if ( !empty($primes[$i]) ) {
 5             foreach ($primes as $key => $item) {
 6                 for ($j = 2 * $i; $j <= $n; $j += $i) {
 7                     unset($primes[$j]);
 8                 }
 9             }
10         }
11     }
12 
13     $primes = array_keys($primes);
14     if ($s) {
15         $sum = 0;
16         foreach ($primes as $k => $v) {
17             $sum += $v;
18         }
19         $primes['sum'] = $sum;
20     }
21     print_r($primes);
22 }
23 
24 primes(100,true);